Particle-size distribution and phosphorus forms as a function of hydrological forcing in the Yellow River.

Samples were collected monthly from January to December in 2010, and daily observations were made during the water-sediment regulation event in June-July 2010. Sequential extractions were applied to determine the forms of P in different particle-size fractions and to assess the potential bioavailability of particulate phosphorus (PP). The results indicated that exchangeable phosphorus, organic phosphorus, authigenic phosphorus, and refractory phosphorus increased with the decreasing of particulate size; conversely, detrital phosphorus decreased with the decreasing of particulate size. The content of bioavailable particulate phosphorus (BAPP) varied greatly in different sizes of particles. In general, the smaller the particle size, the higher the content of bioavailable phosphorus and its proportion in total phosphorous was found in these particles. Hydrological forcing controlled the variability in the major P phases found in the suspended sediments via changes in the sources and the particle grain-size distribution. The variation of particle sizes can be attributed also to different total suspended sediment (TSS) sources. Water-sediment regulation (WSR) mobilized only particulate matter from the riverbed, while during the rainstorm soil erosion and runoff were the main source. The BAPP fluxes associated with the "truly suspended" fraction was approximately 200 times larger than the dissolved inorganic phosphorus (DIP) flux. Thus, the transfer of fine particles to the open sea is most probably accompanied by BAPP release to the DIP and can support greater primary and secondary production.

[Distribution of phosphorus in surface sediments from the Yellow River estuary wetland].

Surface sediments were collected from Yellow River estuary wetland. The distribution of phosphorus in sediments was analyzed with modified SEDEX. The results indicated that the contents of TP in surface sediments varied from 12.12 micromol x g(-1) to 25.37 micromol x g(-1), and the mean value was 20.70 micromol x g(-1), in which the Detrital P and Authigenic P were the main forms. Median particle size was closely related with the distribution of phosphors, Exchangeable P, Authigenic P and Organic P mainly consisted of smaller sediment size, while Detrital P mainly consisted of larger sediment size. The distribution of P in sediment was affected by organic matter. Exchangeable P, organic P and refractory P increased with the increasing TOC. The bio-available phosphorus included exchangeable P, iron-bound P,organic P and ranged from 1.15-6.74 micromol x g(-1), with an average of 4.27 micromol x g(-1) for all sediment samples. The contribution of BAP to TP was 6.35% -30.4%.

[Mixing behavior of nutrients in different seasons at Liaohe Estuary].

The distribution and species of nutrients in the Daliaohe Estuary were studied in April, July and November, 2010. Concentrations of nutrients displayed obviously seasonal variability in the Daliaohe Estuary. Highest concentrations of PO4(3-) -P, DOP, DTP and TP were in April, and the lowest were in July. While the highest PP was in November, the lowest was in July. The contents of NO3(-) -N and NO2(-) -N reached the highest point in July, and the lowest was in April; however, the highest NH4(+) -N, DON and PN were in April and the lowest were in November. The main existing form of TN was NH4(+) -N in April, while in July and November NO3(-) -N was the dominant. The behavior of NO3(-) -N,DIN and TN was conservative in various seasons; the behavior of NO2(-) -N, NH4(+) -N and DON was conservative in April and November, while nonconservative in July, which indicated the exist of the extra source in the interior of the estuary. The SiO3(2-) of the Daliaohe Estuary was conservative, with the highest average concentration in November and the lowest in April.

[Distribution characteristics of COD and DO and its influencing factors in the Daliaohe Estuary].

The concentrations of COD and DO were measured in the Daliaohe Estuary in April, July and November of 2010, and their distribution characteristics and influencing factors were discussed. The results showed that the concentrations of COD were 12.10, 4.42 and 4.38 mg · L(-1) in April, July and November of 2010, respectively. They were mainly influenced by rainfall, runoff and municipal sewage. COD values decreased with the increasing DO from the inner of Daliaohe Estuary to adjacent waters. Spatial distribution of COD was mainly controlled by agriculture and urban sewage and tides. The concentrations of DO were 8.46, 4.23 and 10.30 mg · L(-1) in April, July and November of 2010, respectively, and were mainly influenced by temperature and oxygen consumption of organic matter. Hypoxic zone was found in the low-salinity area in summer, which was mainly controlled by excessive emission of organic matter and nutrients in Yingkou, tidal effects and long residence time of water in the estuary.

[Forms and distributions of particulate phosphorus in the surface sediments of North Yellow Sea].

Surface sediments were collected from the North Yellow Sea in October 2007. The sediments were analyzed with modified SEDEX to obtain six forms of phosphorus. The results indicate that among the total phosphorus the detrital phosphorus and authigenic phosphorus are the main forms and the content varies from 25.7 to 122.5 microg x g(-1) and from 5.7 to 176.2 microg x g(-1), respectively, which taking up 17.0% -56.9% and 10.2% -49.8% of the total phosphorus. The content of exchangeable phosphorus, extractable organic phosphorus, iron-bound phosphorus and refractory phosphorus ranges from 5.5 to 43.9, from 4.1 to 41.4, from 2.3 to 26.7, from 6.0 to 33.6 microg x g(-1), respectively. Detrital and authigenic phosphorus are the major forms of the total phosphorus, indicating that the natural input is the major source of particle phosphorus in the study area. The content of iron-bound phosphorus is low, indicating that human input is minor in the area; mass fraction of the extractable organic phosphorus and refractory organic phosphorus is low, indicating that there is a low organic content while the main form of the total phosphorus is inorganic in the surface sediments of this area. Bioavailable phosphorus as exchangeable phosphorus, extractable organic phosphorus and iron-bound phosphorus account for 6.7% - 33.2% of the total particle phosphorus, indicating that bioavailability of phosphorus in the surface sediments is low.

[Composition of n-alkanes in soils of the Yellow River Estuary Wetlands and their potential as organic matter source indicators].

Abstract: Surface soil samples from the Yellow River Estuary Wetlands were analyzed for total organic carbon (TOC) and n-alkanes. Molecular indicators of n-alkanes were calculated and their potential as organic matter source indicators was discussed and compared among different sampling areas and times. C25-C33 n-alkanes with odd-to-even predominance were observed in most surface soils of the wetlands, suggesting the dominant contribution of terrestrial higher plants for the soil organic matter (SOM), and the ubiquitous presence of unresolved complex mixture indicated the presence of petroleum contamination. Total n-alkane concentrations in soils varied from 0.57 microg x g(-1) to 3.90 microg x g(-1), and distinct spatial and temporal differences were observed. In April 2009 (dry season), total n-alkane concentration was higher than that in June 2009 (during water-sediment regulation) with the maximum concentration observed at the core area of the wetlands, followed by the north side of the Yellow River after the last pontoon bridge, and the abandoned channel area of the Yellow River. The opposite trend of total n-alkane concentration was observed in June. The variation of total n-alkane concentration at two sampling time points were positively correlated with TOC and negatively correlated with sediment grain size, suggesting the influence of hydro-environment on the accumulation of soil organic matter. Molecular indicators of n-alkanes, such as average chain length (ACL), odd-even predominance (OEP), alkane index (AI), carbon preference index (CPI) and Terrigenous/ Aquatic Ratio (TAR) indicated that the maturity of organic matter in soils of the wetlands was low, and the dominant source of the SOM was terrestrial higher plants and mainly herbaceous plants. Compared with other indicators, TAR is better in reflecting the variation of hydro-environment.

[Research advances in the effects of environmental factors on the growth and development of Aurelia spp].

Aurelia spp. is a cosmopolitan coastal species, and also, one dominant species of large jellyfish in the coastal waters of China. In recent years, Aurelia spp. bloom events occur frequently in the world, causing severe damage to marine ecosystems, coastal economy, and society development. Aurelia spp. has a complicated life history comprising a benthic asexually-reproducing polyp generation and a sexually-reproducing medusa generation, and various vegetative reproduction (budding, strobilation, and podocyst production) and sexual reproduction. Surrounding physical and biological factors affect each growth stage of Aurelia spp., especially the juvenile stage of planktonic-benthic life cycle, which has major effect on the population dynamics of Aurelia spp. This paper reviewed the research advances in the effects of environmental factors on Aurelia spp. at its different growth and development stages, and discussed some problems worthy of further study, aimed to provide useful reference for the research of the key factors controlling the jellyfish blooms in coastal waters of China.

[Phosphorus forms of the suspended particulate matter in the Yellow River downstream during water and sediment regulation 2008].

Suspended particulate matter samples were collected from Lijin Station on the Yellow River during the 2008 water and sediment regulation. Using water elutriation method, samples were physically separated according to grain size, and phosphorus forms were detected by the improved SEDEX technology. Results show that authigenic apatite phosphorus and organic phosphorus are the dominant forms of the particulate phosphorus. During water and sediment regulation, concentrations of total particulate phosphorus, loosely adsorbed phosphorus, organic phosphorus and refractory phosphorus are lower than those in other time of the year, while the concentration of detrital fluorapatite phosphorus is higher than that in other time. Grain size is the primary variable in the determination of the content of various particulate phosphorus forms. In fine particles, loosely adsorbed phosphorus, organic phosphorus and refractory phosphorus concentrations are high, while detrital fluorapatite phosphorus concentration is high in coarse particles. About 28.3% of the total particulate phosphorus is in the form of bio-available phosphorus, of which organic phosphorus is the major component. During the water and sediment regulation, the fluxes of sediment, particulate phosphorus and particulate bio-available phosphorus are 6.63 x 10(7) t, 3.42 x 10(4) t, and 8.30 x 10(3) t, which are 83.2%, 78.6%, and 80.2% each of the total fluxes in 2008.

[Distributions of dissolved inorganic mercury in the lower part of the Three Gorges Reservoir].

One year after the first filling stage of the Three Gorges Reservoir(TGR), dissolved inorganic mercury (Hg(DI)) was measured in August 2004. Concentration of Hg(DI) varied from undetection to 82.6 ng x L(-1) with average of 22.7 ng x L(-1). Stratification of Hg(DI) in the TGR was obviously. Concentrations of Hg(DI) were much higher in the layers above 20 m than in deep waters. Concentration of Hg(DI) in the Xiangxi River varied from undetection to 61.4 ng x L(-1) with average of 18.0 ng x L(-1). The Hg(DI) concentration increased obviously after the filling of the TGR. Large amount of Hg was retented with the deposition of sediment in the TGR. The retention of Hg by the TGR needs the further research.